While the present invention will be described with regards to packages comprising plastic containers of the type that are formed, filled and sealed in a continuous operation many other types of packages would also benefit from the present invention. For example, blister pack containers common in the pharmaceutical industry may benefit from the present invention. Once sealed, a package's seal integrity is of great importance in protecting the contents of the package from damage or spoilage. For example, it is estimated that more than 75% of aseptically processed food and beverage spoilage within packages is caused by seal integrity failure. Although there are existing technologies for detecting the integrity of containers and seals on containers, such technologies all suffer from various drawbacks. Prior to now there has been no ideal method available to test on-line irregular shaped packages the integrity of containers and seals on containers of the form, fill and seal variety.
One known method of testing seal integrity is to impart pressure to a chamber enclosing the package seal to see if the pressure holds or drops. If the pressure holds, then the seal integrity is presumed to be satisfactory. If the pressure drops, it can be determined that the seal has been breached at some location.
A second known method for determining seal integrity is to apply a vacuum to a chamber enclosing the package seal to see if the vacuum force decreases. If there is a pressure decay it is a sign that the seal has a leak in it.
A third known method of testing seal integrity is to apply air pressure in a hoop pattern around the entire edge of the seal. If the air pressure drops, it is an indication that the seal integrity is not satisfactory.
None of the known methods of seal integrity testing is well suited for testing multiple packages at one time in a production line setting. Furthermore, the known methods require movement from station to station and extra handling procedures which can increase the possibility of damage to the packages and cause deterioration to the contents in the packages.
The present invention comprises a unique technique to test the container, seal integrity and seal strength of form, fill and sealed containers, and other packages having sealed cover materials, while on-line. Multiple regular or odd shaped containers may be tested at the same time, within seconds. The tested packages may be shipped without mechanical separation, such as 4, 6, or even 12 packs which are commonly preferred by the consumers for convenience. The present invention is capable of detecting leaks in seals and is capable of testing the seal strength to detect weak seals which were not detectable by other methods. Furthermore, the ability to test any number of packages in one single process stroke makes this invention extremely efficient for continuously increasing processing line speed as seen in today's form, fill and seal production process which traditional test systems and methods do not handle satisfactorily.